Airplane wing structure



Oct. 13, 1936. RE. MERCIER AIRPLANE WING STRUCTURE 4 Sheets-Sheet 1 Filed March 9, 1955 -ro RN EYS Oct. 13, 1936. P. E. MERCIER 2,057,339

AIRPLANE WING STRUCTURE Filed March 9, 1955 4 Sheets-Sheet z l N VE N TO R P/er/e 5/22 as! fl/ercvr as @M- 1 1, W

A T TO R N 5Y5 Oct. 13, 1936. P. E. MERCIER AIRPLANE WING STRUCTURE Filed March 9, 1955 4 Sheets-Sheet 3 ATTOR N EY5 06L 1936- P. E. MERCIER AIRPLANE WING STRUCTURE Filed March 9, 1935 4 Sheets-Sheet 4 ATTORNEYS Patented Oct. 13, 1936 UNITED STATES smear car es Application March 9,

1935, Serial No. 10,269

In France September 6, 1934 11 Claims.

In the construction of airplane wings a thickness has to be given to the latter which is as small as possible while the ratio of the span to the chord is often a considerable one.

In order that such small available height may be utilized in the best conditions of wing stiffness and strength an arrangement has sometimes been adopted which is known as box structure with stressed. cover.

Embodiments of wing structure with stressed cover are already known in which generally the stress on the cover is dealt with by a greater or lesser number of webs rigid with said cover. Now, a difficulty with such structures is that they are costly and heavy where a greater number of parallel or slightly convergent webs are used, or that the stress distribution in the cover is notsuitably ensured where the webs are reduced in number. In addition, on account of such arrangement, it is diflficult to aperture the cover adjacent to the junction of the wing with the fuselage or in line with the motor hulls as this is often necessary where it is desired to accommodate such various devices as the landing gear, tanks, bombs and the like within the wing outline according to a common practice.

The invention is, accordingly, directed to the provision of a wing structure including a box type beam with a stressed cover in which the difilculties referred to are avoided, and in a structure embodying my invention, the cover is subjected to uniform bending stresses through a relatively small number of webs, as, for example, two.

Another object of my invention is the combination of the box type beam structure with a two-longeron structure, said structures in this combination being arranged end to end and the transition from the one into the other may then take place, without creating a weak place in the wing or increasing the weight of the same, at any desired point, e. g. adjacent to the junction of the wing with the fuselage or with a motor hull in the case of a multimotor machine, whereby the above mentioned inconvenience connected with the accommodation of various devices Within the out lines at those places is avoided.

A particular provision of my invention consists in connecting one system with the other at three points of junction which preferably transmit only shearing stresses which are at right angles to the wing plane, without taking the dragging stresses into account. V

The box according to my invention generally extends over one half of the wing width in that portion where the thickness of said, wing as defined by the outline of its cross section is a maximum. Thus, in wings of conventional outline, the cross section of the box will extend transversely to the wing from a point on the wing chord located at 5 to 15% of the chord. length from its front end 5 (wing leading edge) to another point located at a distance of 55 to 70% of said end.

For purposes of illustration, an embodiment of my invention will be described hereafter, and this embodiment involves a structure of trapezoidal shape which is most advantageous with respect to weight, torsional resistance, and aerodynamic characteristics.

It is to be understood, however, that the arrangements described may be applied to any other wing shape and even contingently to other structures than airplane wings without thereby departing from the scope of the invention.

Said embodiments are illustrated diagrammatically in the appended drawings. 20

Figure 1 is a perspective diagram showing the general arrangement of the skeleton.

Figure 2 is a plan view.

Figure 3 is a cross section taken on line IIIIII in Fig. 2.

Figures 4 and 5 are cross sections.of two embodiments of cover stiffening members respectively.

Figure 6 is a general plan view of the airplane.

Figures 7 and 8 are perspective views of two embodiments comprising skeletons according to the above mentioned diagrams respectively.

Figure 9 is an elevational view of a modifica tion of the ribs of said wings.

The skeleton of which Figs. 1 to 3 show the general arrangement pertains to a wing the outline of which is indicated in, dot-and-dash lines; said skeleton includes a box type beam C indicated in double lines and a two-longeron system L indicated in treble lines in Figs. 1 to 3, such way of illustration naturally having no other purpose than allowing clearly to distinguish those various portions of the wing.

The beam C which provides the external portion of the skeleton inscribes in plan view within a tetragon. In the example considered such tetragon is irregular, having its longer diagonal directed lengthwise of the wing and its outer acute angle cut away by a truncation M. Besides, any other suitable arrangement and notably a regular diamond shape may be provided depending on the particular cases to be dealt with.

Alined with the sides of said tetragon are arranged the pair of vertical webs A1, A2 of the 55 beam, which unite at a, a at the acute untruncated apex of the diamond, that is, at the one located at the inside, where the thickness of the beam is a maximum.

The cover V of the beam comprises stiffening members at its inside faces, which are designed to give sufficient stiffness to the same and as they are compressively strained to make it resistant to such eiforts as result from bending stresses.

Said stiffening members are oblique with respect to the webs A1, A2, and those which lead to one and the same web are preferably parallel to one another.

In the example considered said stiffening members are distributed in two series-R1, R2 connecting the sides of each obtuse angle b, 1) respectively.

Embodiments of the shapes R, R contemplated for said stiffening members are shown in Figs. 4 and 5.

The cover preferably consists of strips arranged parallel to the stiffening members and the thicknesses of which may be unequal.

The structure L located beyond the beam toward the fuselage comprises on one hand a pair of longerons L1, L2 arranged in line with those portions of the beam webs A1, A2 respectively providing the sides adjacent to truncation M and on the other hand a transverse strut E which is led through apex a, a.

According to another modification contemplated by my invention the longerons L1, L2 instead of being convergent towards the wing tip may be parallel, each longeron in one wing producing the corresponding longeron of the other wing.

The connection of the beam with the twolongeron structure described is provided at three places, one of which is the inner acute apex a a of the beam while the two others are the two obtuse apices b b, b b of the same.

Practically, such connections which involve only the Webs of longerons L1, L2 and those of the beam which are indicated at A1, A2 may be embodied as hinges or angle-iron and bolt or knuckle-joint connections.

The stresses through said connections are directed on junction lines a a, b b, b b, so that the latter are really equivalent to connection points.

The shearing stresses in the webs A1, A2 of the beam along the junction line of the same with its cover set up strains in the latter which are directed obliquely to the webs, this resulting from the shape of the beam and the direction of the stiffening members.

The webs A1, A2 and the thicknesses of the cover strips together with the stiffening members thereof are so dimensioned that the component forces due to the obliqueness of the lines of tension with respect to the webs are balanced in each web pair in every wing cross-sectional plane.

Said component forces, such as m r and n t (Fig. 2) will urge the webs A1, A2 apart or toward each other depending on whether the cover is compressively or tensionally stressed. In the case shown the cover at point m exerts a pull m k which compensates with the shearing stress m 9' on the web, and the component forces m r and n it applied at two corresponding points m, n or either web will urge the same towards each other.

Said forces are dealt with by bracing bars or rib elements N.

The effect of such forces on the resistance of the cover to compression is thus a favourable one inasmuch as the same is tensioned crosswise to the direction of the thrust.

In the case of a comparatively thin wing and in order to utilize the central cover band which is not directly related to the Webs on account of truncature M the system of the web pair A1, A2 may be supplemented with a third web arranged in the medial plane of the beam as indicated by the dotted line As and containing the maximum thicknesses of the outlines.

The third web referred to may lie in a plane along which the beam is dismantled, in which case, the beam comprises a pair of companion elements assembled on said medial plane, whereby construction and maintenance are facilitated.

According to another arrangement contemplated by my invention the wing may be made in two parts arranged above each other. The ribs then are also made of two parts and the upper and lower wing halves are constructed as separate units by fitting the related elements on said rib halves, after which the latter are assembled and the webs providing the beam sides are fitted.

Figure 6 illustrates a twin-engine airplane comprising wings of the above described type. The hull of an engine F at either side is located substantially at the junction between the beam C and the two-longeron structure L of the related wing.

Embodiments of the above described arrangements are illustrated in more detailed manner in Figs. 7 to 9.

The longerons in Fig. '7 are visible at L and one web of the beam at A. The cover comprises strips B having their edges parallel to the stiffening members R1, R2 on which they are secured.

N1 designates a connection rib located at the place where the beam and the two-longeron structures are assembled.

Such connection is secured at the apex a a. of the beam by means of hinges I and at each apex b b by means of a pin 2.

The portion of the beam which is broken away discloses a rib which according to the arrangement described above is made in two halves 3a, 3b arranged one above the other and having an overlap 30 at the ends thereof for assembly.

In the modification shown at Fig. 8 the connection between the two-longeron structure (one longeron of which is shown at L), connection rib N1 and the beam webs such as A comprise hinges I at apex a a and a hinge 4 at each apex b b.

Figure 9 illustrates another embodiment of a rib which according to the arrangement described hereinbefore comprises two halves 5a, 5b assembled in the wing longitudinal medial plane e. g. by means of hinges 6.

I claim:-

1. In an airplane wing, a supporting structure, a box-like wing member supported at opposite lateral sides by said supporting structure and extending outwardly therefrom, said boxlike structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally extending sides defining obtuse angles, transversely-spaced stiffening members connecting each longitudinally extending side with its adjacent converging side of said box-like structure, means for connecting opposite lateral sides of said box-like structure to the supporting structure adjacent the juncture of said longitudinally-extending and said converging sides, and means for connecting the inner ends of said converging sides to said supporting structure.

2. In an airplane wing, a supporting structure comprising a pair of longerons, a box-like wing member supported by said longerons and extending outwardly therefrom, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally-extending sides defining obtuse angles, and transversely-spaced stiffening members connecting each longitudinally-extending side with its adjacent converging side of said box-like structure, said box-like structure being connected to said longerons adjacent the juncture of said longitudinally-extending and said converging sides.

3. In an airplane wing, a supportng structure comprising a pair of longerons and a transversely extending member connecting said longerons, a box-like wing member extending outwardly from said longerons and the transversely extending member, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally-extending sides defining obtuse angles, transversely-spaced stiffening members connecting each longitudinally-extending side with its adjacent converging side of said box-like structure, means for connecting opposite lateral sides of said boxlike structure to said longerons, and means for connecting the inner ends of said converging sides to said transverse member.

4. In an airplane wing, a supporting structure comprising a pair of longerons and a transversely extending member connecting said longerons, a box-like wing member extending outwardly from said longerons and the transversely extending member, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinallyextending sides defining obtuse angles, a series of transversely-spaced, substantially parallel stiffening members connecting each longitudinallyextending side with its adjacent converging side of the box-like structure, transversely-extending members connecting the longitudinally-extending and the converging sides, means for connecting opposite lateral sides of said box-like structure to said longerons, and means for connecting the inner ends of said converging sides to said transverse member.

5. In an airplane Wing, a supporting structure comprising a. pair of longerons, a box-like wing member supported by said longerons and extending outwardly therefrom, said box-like structure having sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinallyextending sides defining obtuse angles, a series of transversely-spaced, substantially parallel stiifening members connecting each longitudinallyextending side with its adjacent converging side of the box-like structure, transversely-extending members connecting respectively the converging and the longitudinally-extending sides, means for connecting opposite lateral sides of said box-like structure to said longerons, and a covering for the upper and lower surfaces of said box-like structure.

6. In an airplane wing, a supporting structure, a box-like wing member supported at opposite lateral sides by said supporting structure and extending outwardly therefrom, said box-like structure being of general pentagonal shape and having two longitudinally-extending, lateral, weblike sides, and two web-like sides adjacent said longitudinally-extending sides converging inwardly and with said longitudinally extending sides forming obtuse angles, and transverselyspaced stiffening members connecting each longitudinally-extending side with its adjacent converging side of said box-like structure.

7. In an airplane wing, a supporting structure, a box-like wing member supported at opposite lateral sides by said supporting structure and extending outwardly therefrom, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said boxlike structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally-extending sides defining obtuse angles, and transversely-spaced stiffening members connecting respectively the longitudinallyextending and the converging sides of said boxlike structure.

8. In an airplane wing, a supporting structure, a box-like wing member supported at opposite lateral sides by said supporting structure and extending outwardly therefrom, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally-extending sides defining obtuse angles, and a series of substantially parallel transverselyspaced stiffening members connecting each longitudinally-extending side with its adjacent converging side of the box-like structure.

9. In an airplane wing, a supporting structure, a box-like wing member supported at opposite lateral sides by said supporting structure and extending outwardly therefrom, said box-like structure having lateral sides thereof extending longitudinally of the wing, other sides of said box-like structure adjacent said longitudinally-extending sides converging inwardly and with said longitudinally extending sides defining obtuse angles,

transversely-spaced stiffening members connecting each longitudinally-extending side with its adjacent converging side of said box-like structure, and transversely-extending members connecting the longitudinally-extending and converging sides.

10. An airplane wing structure as set forth in claim '7 in which the stiffening members connecting each longitudinally-extending side to its adjacent converging side are in two series disposed PIERRE ERNEST MERCIER. 

